Process of making self-copying writing paper



Patented Aug. 7, 1923.

PATENT OFFICE.

AXEL GUSTAF EKIL LUNDGBEN, F NOBBiKfiPING, SWEDEN.

PROCESS OF MAKING SELF-COPYING WRITING PAPER.

Ho Drawing.

To all whom it may concern:

Be it known that I, AXEL GUSTAF EMIL LUNnoRnN, a citizen of the Kingdom of Sweden, residing in Norrkoping, Sweden, have invented certain new and useful Improvements in a Process of Makin Self- Copying Writing Paper, of which t e following is a specification.

This invention relates to a process of it making a self-copying writing paper. In the usual process of making copying-paper,

the paper on one side is coated with a mixture of wax or paraffin and a colouring-matter. Owing to the fat nature of paraflin and wax the paper at the same time becomes transparent, making the colour visible through the paper in such a way that writin on the opposite side will not be readab 0.

The object of this invention is now to overcome the difiiculty mentioned "above. The side of the paper to be coated with the colouring-matter is therefore prepared with an acid, that is capable of transforming to paper into parchrnent-paper, for example sulphuric acid, in order that the paper will not be permeated by the fatty substances. Thus prepared this side of the Application filed lanuary lfi, 1922. Serial'flo. 529,707.

paper is coated with the mixture whereafter the other side may be used for writing which gllll be readable even if the paper is very Paper prepared in the way stated above may be used for type-writing as well as for other writing.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is

l. A process of making a self-copying writing-paper, which consists in preparing 40 one side of the paper with an acid, that is capable of transforming paper into parchment-paper, and then coating this same side with a colouring matter.

2 A process of making a self-copying 46 writing paper, which consists in preparin one slde of the paper with sulphuric aci and then coating this same side with a colouring matter.

In testimony whereof I have afiixed my on slgnature.

v AXE]. GUSTAF EMIL LUNDGREH. Witnesses:

Jnrrs Isms, E. Jam. 

